In the art of barrier operators for moving vehicle barriers, such as upward acting garage doors, there have been developments directed toward providing a lightweight, efficient operator with various control features. One desired feature for a barrier operator, including an operator for an upward acting sectional garage door, is to provided as compact a device or apparatus as possible and one which does not require mounting the operator to an overhead structure, such as the garage ceiling. Also considered desirable is an operator which does not occupy space between the horizontal or curved portions of the spaced apart barrier guide tracks. Another desired feature in barrier operators, generally of the type described herein, is the provision of an operator mechanism which may be easily disconnected in the event of a malfunction, but also minimizes the chance of unwanted forcing of the barrier from a closed position to an open position. Still further desiderata include low cost of installation, quiet operation and ease of maintenance or replacement, if needed. The above-mentioned features, as well as other advantages, are provided by the present invention.